Apparatus for casting small solid propellant rocket motors for testing purposes



9 Egg R. M. M ELFEQY, JR 39255372? APPARATUS FOR CASTING SMALL SOLID PROPELLANT BUCKET MQTORS FOR TESTING PURPOSES Filed. July 22, 1965 2 Sheets-Sheet l Rebmir M. Moi-May Ja:

INVENTOR.

Fig 2 Attorney 5' 2, 1966 R. M. M ELROY, JR 392637275 APPARATUS FOR CASTING SMALL SOLID PROPELLANT ROCKET MOTORS FOR TESTING PURPOSES Filed July 22, 1963 2 Sheets-Sheet 2 Robert M. McElroy Jr.

INVENTOR.

BY 11 I,

Attorney United States Patent 3,263,275 APPARATUS FOR CASTliNG SMALL SOLID PRO- PELLANT RQCKET MOTURS FUR TESTING PURPOSES Robert M. McElroy, lira, Huntsville, Ala, assignor to Thiokol Chemical Corporation, Bristol, Pa., a corporation of Delaware Filed July 22, 1963, Ser. No. 296,676 Claims. (til. 18-26) This invention relates to an apparatu for casting small solid propellant rocket motors and, more particularly, to an apparatus for casting a solid propellant rocket motor that is to be used for test purposes.

In evaluating the performance of solid propellants, it has been found desirable to build a test motor of convenient size that is a prototype of the eventual solid propellant rocket motor that is to be flight tested. The test motors are static tested, and the performance of the particular solid propellant that has been cast into the test motor can be carefully evaluated. Due to the size of the test motors, a suitable apparatus had to be provided that would retain the test motor in position so that the solid propellant could be cast therein with a maximum operating efliciency. The apparatus, to retain the test motor for casting, had to be durable, inexpensive, and easily disassembled so that several test motors with various types of solid propellant therein could be expeditiously cast for test purposes.

It is an object of this invention, therefore, to provide an apparatus that will retain a test motor in position to be properly loaded with a solid propellant in the most eflicient and expeditious operation that is considered with such a procedure.

Such an apparatus must include means therein for properly distributing the solid propellant and deaerating the same as it is being cast into the test motor. Such a means must be inexpensive so that it may be expendable, yet must be of a type that can be rapidly reproduced to obtain maximum efficiency without sacrificing any advantage that is consistent with the procedure that must be followed in casting the test motor.

It is, therefore, another object of this invention to provide an apparatus of this type that is simple in construction and inexpensive, but which will perform with maximum efiiciency in an expeditious manner.

With the above and other objects and advantages in view, the invention consists of the novel details of construction, arrangement, and combination of parts more fully hereinafter described, claimed, and illustrated in the accompanying drawings in which:

FIGURE 1 is a vertical sectional view, partly in elevation, of an apparatus forming the instant invention.

FIGURE 2 is an elevational view, partly in section, of the head end of the apparatus of FIGURE 1.

FIGURE 3 is a perspective view, partly in section, of the aligning and deaerat-ing spider, and

FIGURE 4 is an elevational view of the aft end of the core that is used in the apparatus of FIGURE 1.

Referring more in detail to the drawings wherein like parts are designated by like reference numerals, the reference numeral is used to generally designate the apparatus embodying the invention.

The apparatus 10 is arranged to properly retain a cylindrical rocket motor case 11 in position so that an uncured solid propellant can be cast therein in the conventional manner.

In order to perform the function for which it was conceived, the apparatus 10 comprises a head end tubular sleeve 12 and an aft end tubular sleeve 13. An annular seat 14 of a size to fit one end of the motor case 11 is machined into the internal surface 15 of the head end sleeve 12 and an annular seat 16 of a size to fit the opposite end of the motor case 11 is machined into the internal surface 17 of the aft end sleeve 13.

The sleeves 12 and 13 are positioned so that the seats 14 and 16 are in confronting relation to each other whereby the seats 14 and 16 will receive therein the opposite ends of the motor case 11. A gasket 18 provided in each of the seats 14 and 16 seals the ends of the motor case 11 in the respective seats 14 and 16. Formed integral with the sleeve 12 in circumjacent relation to the seat 14 therein, is an annular, right-angularly-extending flange 19 and a similar annular flange 20 is provided on the sleeve 13 in circumjacent relation to the seat 16 therein. Suitable clamping means, for example, machined tie-bolts 21 are extended through the flanges 19 and 20 so that when a nut and Washer assembly 22 is threaded onto each of the bolts 21 and tightened, the sleeves 12 and 13 and motor case 11 will be forced into rigid unitary relation to each other, as shown in FIG URE 1.

A beveled rim 23 is provided in the outermost end of the sleeve 12, and such rim provides a seat for the aligning and deaerating spider 24. The spider 24 has four blades 25, 26, 27, and 28 respectively; and the outer longitudinal edges of each of the blades are beveled, as shown at 29 in FIGURE 3. A bore 30 extends into the medial portion of the spider 24; and a truncated conical formation 31 that is integral with the beveled edges 29 of the blades 25, 26, 27, and 28 surrounds the bore 30 as it extends outwardly through the beveled edges 29 of the blades 25, 26, 27, and 28, as shown in FIGURE 3. The spider 24 is expendable and is made from a durable plastic material of conventional composition.

The outermost end of the sleeve 13 has a U-shaped strap 32 pivotally connected thereto by pins 33; and an adjustable, machine bolt 32 is mounted in the medial portion thereof.

When the uncured solid propellant is to be cast into the motor case 11, a core 35 of any desired configuration is positioned in the motor case 11. The head end 36 of the core 35 is provided with an outwardly extending alignment pin 37 which is positioned in the bore 30 in the spider 24; and the aft end 38 of the core 35 is provided with an integral discoid alignment flange 39. The flange 39 is of a size to be slidably received in the sleeve 13 and,

with the aid of the spider 24, properly aligns the core 35' in the motor case 11.

The flange 39 is provided with a circular row of vents 40. A stem 41 integral with the flange 39 extends outwardly from the center of the flange 39 in perpendicular relation thereto and in axial alignment with the core 35. A transverse opening 42 is provided in the stem 41 for the handling of the core 35 as it is inserted into and withdrawn from the motor case 11.

With the core 35 in position as previously described and as shown in FIGURE 1, the strap 32 is moved into position so that the bolt 34 will be able to engage the outer end of the stem 41; and when the bolt 34 is tightened, the core 35 is rigidly retained in the motor case 11 so that it will not move in any direction when the uncured solid propellant is cast into the motor case 11.

Uncured solid propellant is introduced into the outer end of the head sleeve 12 by a source of supply not shown; and as it flows past the spider 24, the spider tends to break up the flow of the solid propellant. The beveled edges 29 of the blades 25, 26, 27, and 28 prevents any entrapment of air in the propellant as it flows past the spider 24. As the propellant is cast into the motor case 11, any air trapped therein will escape through the vents 40 in the alignment flange 39. The propellant is cast into the motor case 11 to some predetermined level, and the source of supply is then removed, and a cap, not shown, is then placed over the end of the head sleeve 12; and the apparatus, with the motor case 11 therein, is stored for the curing of the solid propellant.

After the solid propellant has been cured, the bolt 34 is loosened, the strap 32 is pivoted laterally, and the core 35 is Withdrawn from the solid propellant. Nuts 22 are loosened, and the sleeves 12 and 13 are removed from contact with the ends of the motor case 11. Any excess solid propellant is then trimmed from the motor case 11 level with the opposite ends thereof. The spider 24 will remain in the excess propellant and be discarded therewith after the excess propellant has been trimmed from the motor case 11.

Such a structure as previously described eliminates excess cleaning of the sleeves 12 and 13 after they hav been removed and before the apparatus 10 is again assembled for reuse. The disposal of the spider 24 eliminates also the cleaning thereof, since a new one will be used when the apparatus 10 is again used to prepare another rocket motor.

There has thus been provided an apparatus that is adapted for casing small motors; and it is believed that, from the foregoing description, the structure and manner of use of the apparatus will be clear to those skilled in the art, it being understood that changes therein may b resorted to providing that such changes fall within the spirit of the invention and the scope of the appended claims.

. Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An apparatus for use with the casting of solid propellant rocket motors comprising a pair of tubular sleeves for engaging the opposite ends of a motor case, each of said sleeves having a seat therein to receiv the respective ends of the motor case, each of said sleeves having an integral disc flange thereon, tie bolts extended through said flanges for retaining the motor case and said sleeves in fixed rigid relation to each other, core means for insertion into said sleeves, aligning means in said sleeves and integral with said core means for properly aligning said core means in the motor case, and means connected to said sleeves and engaging said core means to retain said core means in fixed relation to said sleeves.

2. An apparatus for use with the casting of solid propellant rocket motors, comprising means for engaging the opposite ends of a motor case, means for retaining the motor case and said first means in fixed rigid relation to each other, core means for insertion into said first means, aligning means in said first means for properly aligning said core means in the motor case, said aligning means comprising a four-bladed spider having the longitudinal edges of said blades beveled and discoid flange having a circular row of vents therein integral with said core means, and means connected to said first means and engaging said core means to retain said core means in fixed relation to said first means.

3. An apparatus for use with the casting of solid propellant rocket motors, comprising means for engaging the opposite ends of a motor case, means for retaining the motor case and said first means in fixed rigid relation to each other, core means for insertion intosaid first means, aligning means in said first means and integral with said core means for properly aligning said core means in the motor case, and a pivotally mounted strap connected to said first means and having an adjustable screw bolt therein for engaging the end of said core means to retain said core means in fixed relation to said first means.

4. Th combination with a motor case of a pair of tubular sleeves for engaging the opposite ends of said motor case, tie bolts connected to said sleeves for retaining said motor case and said sleeves in fixed relation -to each other, core means mountably inserted into said sleeves and said motor case, aligning means in one of said sleeves and integral with said core means for aligning said core means in said sleeves and in said motor case, and means pivotally connected to one of said sleeves and engaging said core means for retaining said core means in fixed relation to said sleeves and said motor case.

5. An apparatus for use with the casting of solid propellant rocket motors comprising a pair of tubular sleeves for engaging the opposite ends of a motor case, a seat in each of said sleeves for receiving the respective end of the motor case, a disc flange on each of said sleeves, tie bolts extending through said flanges for retaining said sleeves and the motor case in fixed relation to each other, a core for insertion into said sleeves and the motor case, an outwardly extending alignment pin on one end of said core, an aligning spider having a bore in the medial portion thereof positioned in one of said sleeves for engagement with the alignment pin on the said one end of said core, an aligning discoid flange having a circular row of vents therein integral with one end of said core, and a U-shaped strap pivotally connected to the other of said sleeves, and having a screw bolt thereon for engaging the free end of said core for retaining said core in fixed relation to said sleeves and the motor case.

References Cited by the Examiner UNITED STATES PATENTS 274,728 3/1883 Crutsinger 18-29 342,420 5/1886 Bingham 18 29 1,367,341 1/1921 Abbott 264--26 1,457,290 5/1923 Schroeder 18 29 X 1,745,482 2/1930 Goodwin 18-29 x 2,258,810 10/1941 Rabezzana et al. 264-262 X 2,327,113 8/1943 Kratz 264 -261X 2,924,851 2/1960 Birckhead 18-39 X 3,027,597 3/1962 McCurdy 18--26X 3,100,676 8/1963 Christie 1829 x WILLIAM J. STEPHENSON, Primary Examiner. 

1. AN APPARATUS FOR USE WITH THE CASTING OF SOLID PROPELLANT ROCKET MOTORS COMPRISING A PAIR OF TUBULAR SLEEVES FOR ENGAGING THE OPPOSITE ENDS OF A MOTOR CASE, EACH OF SAID SLEEVES HAVING A SEAT THEREIN TO RECEIVE THE RESPECTIVE ENDS OF THE MOTOR CASE, EACH OF SAID SLEEVES HAVING AN INTEGRAL DISC FLANGE THEREON, TIE BOLTS EXTENDED THROUGH SAID FLANGES FOR RETAINING THE MOTOR CASE AND SAID SLEEVES IS FIXED RIGID RELATION TO EACH OTHER, CORE MEANS FOR INSERTION INTO SAID 